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The development of postural stability in children with and without visual impairments (VI) was compared. Thirty eight subjects (4- 12 years old) without VI and 12 subjects with VI (5- 12 years) took part. Stability was measured in 4 quiet standing tasks (normal or foam surface, eyes open (EO) or eyes closed (EC)) and by measuring stability limits (SL) in the anterio-posterior (a-p) and lateral (lat) planes. Results for control subjects were compared using Pearson correlation coefficients, analysis of variance, and analysis of covariance (height as the covariate). For quiet standing tasks, outcome parameters were the standard deviation (SO) of the centre of pressure (CP) in the a-p and lat planes, and mean velocity (vel) of CP movements. For the leaning tasks, SL was measured (normalized to the base of support) in the a-p and lat planes, and SL was compared to CP. Individual results for subjects with VI were compared qualitatively to control subjects. For control subjects, stability increased with age. Subjects with VI were less _stable than controls on all outcome parameters. Differences between groups were more apparent as age increased, particularly for EO conditions. This could indicate a slower pattern of development for subjects with VI compared to controls. The groups were different both in the EO and EC conditions, indicating that postural control with EC is not the same as postural control with a VI, and that vision is important to the development of postural control in children. / Thesis / Master of Science (MSc)

The present study was designed to investigate the effects of a progressive strength training program on quiet postural sway and stability limits in healthy males (n=8) and females (n=12) aged 60-80 years. The ability of the subjects to utilize visual information (eyes open vs. eyes closed) to improve quiet postural sway and stability limits was also examined. Vision, was found to significantly improve quiet postural sway (lat and a-p) and stability limits (a-p). Vision improved stability limits (lat) for the male subjects but not for the female subjects. The strength training did not significantly improve any of the balance measures but a gender by training interaction was found for quiet postural sway (normalized to stability limits) in the a-p direction. The male subjects quiet postural sway decreased after the strength training and their stability limits increased, The greatest improvements in balance were noted for the subjects who had substantially higher baseline levels to begin with. Exercise was found to improve muscle strength and this increase may have contributed to the improvements in balance noted. / Thesis / Master of Science (MS)

The purposes of this study were: (1) to determine whether there was a correlation between a quantitative assessment of postural sway , and a clinical assessment of postural stability, in patients diagnosed with idiopathic Parkinson's disease (PD); (2) to plot individual diurnal changes in postural sway characteristics of PD patients over an eight-hour time period; (3) to plot day to day changes in individual postural sway characteristics of PD patients: (4) to determine whether there was a difference in the postural sway characteristics of parkinsonians, with and without vision; (5) to determine whether there was a difference in the postural sway characteristics of the same individuals when using either Sinemet or Oeprenyl. Three male PD patients were recruited into this study. Each subject stood on a stable force platform (AMT1 OR6-5-1). Measurements included the standard deviations of the coordinates of the centre of pressure (COP) in the anterior-posterior (a-p) and lateral (lat) directions, the mean velocity of sway, and area of sway. These dependent measures were evaluated in a "quiet standing" condition, once with the eyes open (EO) and once with the eyes closed (EC). These procedures were carried out ten times over the course of an eight hour day. Each subject was tested two days while taking eight hour day. Each subject was tested two days while taking Sinemet, and two days while on the Deprenyl regimen. Secondly, at two periods of each test day, each patient was evaluated using the postural assessment section of the Sears Parkinson's Assessment Form (SPAF). The results were: (1) group analyses and individual analyses established the evidence of significant correlations between both the quantitative measures of postural sway (force platform) and the qualitative assessment tool (SPAF): (2) significant variability was evident in the analysis of individual data plots: (3) no statistically significant differences were observed tor any subject when measured from day to day; (4) generally, vision was a stabilizing factor in postural control, however, this was quite variable for each subject; (5) significant improvements in postural stability were observed with the introduction of Deprenyl for one out of three subjects. These findings are discussed in terms of their clinical and behavioral importance, with specific reference to Physiotherapy. / Thesis / Master of Science (MS)

Workload is defined as the cost incurred by an individual, given their capacities, while achieving a particular level of performance on a task with specific demands. Demands of a task or combination of tasks may include maintaining postural stability, executing physical actions, and/or performing cognitive tasks. While there have been attempts to establish a physiological measure of concurrent physical and mental workload, as yet there has been no work towards developing a single subjective method of evaluation. Select subjective assessment methodologies were evaluated quantitatively during laboratory-based experiments. Concurrent execution of mental and physical activity was required at various levels, since it was desired to be able to measure mental workload, physical workload, and also evaluate their interaction. Measurements of task performance were investigated to evaluate the effects of combined mental and physical demands and establish which subjective assessments were accurate and sensitive to changes in workload. The utility of existing subjective assessment tools created for one domain appeared to be limited when evaluating multi-task situations requiring substantial mental and physical activity. Further clarification of the impact of different types of physical demand on cognitive processing, performance and subjective workload assessment of a constant mental task was addressed in the second experiment. This experiment investigated the effect of several activity types, specifically global versus localized effort, changes in load, and different task frequencies. The results provided support that the type of activity, load and frequency of task influence subjective mental workload assessment scores and performance. Not all existing assessment tools accurately represented an individual's ability to perform a task when there was a combination of physical and mental demands. A unidimensional tool is suggested as a screening tool to identify situations requiring excessive or increased mental workload. Alternative methods, possibly a new multidimensional tool, should be developed to obtain more detailed information so ratings of workload for different tasks may be compared. Effectiveness of a subjective stability assessment tool was evaluated in situations demanding mental activity while maintaining an upright posture. Tests were performed over a wide range of conditions, including various mental loads, sensory conditions, and postural stances. The purpose was to determine the effects of each task variation on the perception of postural stability. Postural sway increased with task difficulty, regardless of the source (i.e. postural stance, visual condition, mental workload). The addition of mental workload did not alter the non-linear relationship between objective measures of postural sway and perceptions of postural stability. Since decrements in balance are well perceived, subjective assessment tools may be incorporated in control strategies to minimize falls. / Ph. D.